1. Field of the Invention
The present invention relates to a readhering and removable adhesive composition. The present invention relates to a readhering and removable adhesive in a solid stick form which can be evenly coated onto a surface.
2. Description of the Prior Art
Prior art adhesive available in solid form are known in the art. These adhesives, however, are commonly intended for use as a permanent adhesive, and therefore once a substrate is coated with the adhesive and the coated substrate applied to a receiving surface, it is not intended to be removable therefrom. One common adhesive of this type is often referred to as a "glue stick" or alternatively, an "adhesive applicator crayon". Solid or semisolid permanent adhesives available in a stick or crayon form are typically composed of water soluble or water dispersible adhesive components.
U.S. Pat. No. 3,576,776 is illustrative of the prior art. This reference discloses an "adhesive applicator crayon" which contains a water soluble film forming adhesive component which is typically polyvinyl-pyrrolidone. The formulation disclosed in this reference also includes a gel-forming salt, typically sodium stearate and aqueous liquid medium which may be water or mixtures of water and water miscible organic solvents. Constituents such as glycerine or ethylene glycol are typically included in the formulation disclosed in this reference to aid in moisture retention and to facilitate the ease with which the adhesive may be applied to a receiving substrate. The active adhesive component in the formulation is designated a water soluble or water dispersible film forming adhesive component. It would be recognized by those skilled in the art that the list of water soluble or water dispersible film forming adhesive components as disclosed in this reference, e.g., at column 2 lines 35-61 including the preferred polyvinyl pyrrolidone are permanent adhesive components, not intended for reusable, removable and readhering application. There is, furthermore, no intent expressed in this reference for use of the adhesive crayon formulation as a removable and readhering type of adhesive. Rather the adhesive formulation disclosed in this reference will form a permanent bond between two substrates.
Readhering adhesives, in contrast, when applied to a substrate should permit adherence of the coated substrate to a free contact surface, permit removal of the coated substrate and allow readherence of the coated substrate to another free surface.
Readhering adhesives are available, but heretofor are not successfully been commercialized in a semisolid or solid stick form from which even coatings of adhesive may be directly applied to a solid surface. Although attempts in the past may have been made to formulate a removable adhesive in a solid gelled form, such prior art formulations have been difficult to produce for a number of reasons. In practice, it has been found quite difficult to produce a formulation in jelled form which has just the right amount of tack that an adhesive bond between the coated substrate and a contact substrate may be obtained but yet exhibit the proper degree of removability that the adhesive coated substrate, may be removable from the contact substrate without tearing the substrates and without leaving behind residual adhesive. Additionally, it has proved difficult to formulate a removable adhesive in solid form, which exhibits the required degree of tack that enables initial bonding between the coated substrate and the contact surface, but yet permits readherence of the adhesive coated substrate once it has been removed from the contact surface.
Paper substrates which have been pre-coated with removable, readhering adhesives have, in recent years, become commercially available. One commonly known product of this type is marketed under the trade designation POST-IT note pads from the 3M Company. Although the POST-IT note pads exhibit sufficient tack, removability and readhering characteristics, they have the disadvantage to the user that they are readily available only in precoated, predesignated sizes and also are considered to be relatively quite expensive.
Accordingly, it is an object of the present invention to provide a gelled solid or semisolid adhesive which is readily coatable onto substrates typically paper, and exhibits sufficient tack, such that the coated surface easily adheres to a contact surface.
It is an important object of the present invention that the gelled adhesive exhibits sufficient tack which permits the adhesive coated substrate to adhere to a contact surface, but yet has the property that permits the adhesive coated substrate to be readily removable therefrom.
Another objective of the invention is to provide a gelled solid or semisolid adhesive which exhibits a high degree of removability and readhering characteristics permitting a substrate coated with the adhesive to be applied, removed and reapplied a number of times to and from a free contact surface without adding additional adhesive.
Another objective of the invention is to provide a gelled solid or semisolid adhesive which is readily coatable onto a substrate and which easily adheres to a contact surface, but yet does not leave behind residual adhesive on the contact surface when the adhesive coated substrate is removed therefrom.